LED drivers and other lighting power circuits often employ flyback, buck-boost, and buck converters to provide DC power for driving a light source. To provide closed-loop control for such converters, a signal proportional to the output current is used as a control variable, typically via current sensing resistors in the output circuit. Direct output sensing cannot be done in converters in which the output is isolated from the input by a transformer, in which case the output current has been sensed using current transformers and/or optical isolation components. These components, however, occupy circuit board space and are costly. Moreover, direct sensing is undesirable in low power converters, with or without isolation, as any direct sensing of the output current significantly lowers the driver efficiency. While current transformers may minimize the impact on efficiency, these extra components are bulky and expensive in comparison to the cost of the converter itself, and impact the compactness of the converter. Accordingly, there is a need for improved output current sensing capabilities and systems for closed loop power converter control.